Bacterial ribosomes contain three different RNA molecules and fifty to sixty different protein molecules. We wish to understand the complex series of events which originate in the transcription of the more than sixty genes for these components and culminate in the formation of the complex, and yet specific, structure of the organelle. More specifically, we wish to identify (as many as possible) genes coding for ribosomal proteins (r-proteins) and study their genetic organization and the control of their expression. We have recently isolated lambda transducing phages which carry many r-protein genes of E. coli. Starting with these phages, we have isolated mutant transducing phages which have mutations, such as deletions, insertions, and point mutations, in the r-protein genes. Using these mutants, we will map r-protein genes, define transcriptional units, and find any regulatory genes involved in r-protein synthesis. We have also used DNAs (and their fragments) from these transducing phages as templates to synthesize r-proteins in vitro. We shall continue this approach to map the genes and to learn factors which influence r-protein synthesis in vitro. Genetic organization of genes for rRNA and RNA polymerase subunits will also be studied.